Cutting tool

ABSTRACT

A tool comprising a cutting section, on which a multiplicity of blades or cutting edges and flutes are formed; a shank section, which forms a chucking section on a side which faces away from the cutting section, wherein a number of fluid channels which corresponds to the number of flutes is formed in the chucking section, which channels in each case have an axial discharge opening and lead along the shank to an associated flute of the cutting section. Also, a method for supplying the blades of such a tool with a pressurized fluid.

This application is a continuation of International Application No.PCT/DE2008/000739 having an international filing date of Apr. 30, 2008,published in Germany on Nov. 27, 2008 under PCT Article 21(2), theentirety of which is incorporated herein by reference. This applicationclaims benefit under 35 U.S.C. 119 sections (a)-(d) of GermanApplication DE 10 2007 023 167.0, filed May 20, 2007, the entirety ofwhich is incorporated herein by reference.

BACKGROUND

The invention relates to a rotatably drivable cutting tool, for example,a fine machining tool such as a reamer.

Such tools must meet a wide variety of demands. On the one hand,increasingly higher machining accuracy is demanded of such tools, whichrequires a high dimensional accuracy of the blade positioning and a highstability during dynamic loading of the blades and shank. On the otherhand, an increasingly longer service life is demanded of such tools, forwhich reason a coolant/lubricant supply system is regularly integratedin such tools. This coolant/lubricant supply system which is integratedin the tool is intended to ensure that the most loaded regions of thetool receive a sufficient supply of coolant/lubricant at any time duringuse.

There are various approaches in the prior art for designing generictools with integrated coolant/lubricant supply systems.

The document DE 10347755 A1 discloses a generic tool configured as ahigh-speed reamer, in which a cutting head, which is connected in arotationally and axially fixed manner to a shank section and can befabricated from a hard material such as a sintered material, is suppliedwith coolant/lubricant by means of a central coolant/lubricant supplychannel in the tool shank and a radial channel system in or at theinterface to the cutting head. The radially outer mouth openings of theradial channel system are covered by a coolant-conducting sleeve whichextends in the direction of the tool tip as far as a runout region ofthe flutes and can thus ensure that the supplied coolant/lubricant canbe fed into the flutes with minimal losses.

This known coolant/lubricant supply system which is integrated into theshank tool is also suitable for what is known as MQL (Minimal Quantity.Lubrication) technology, according to which the coolant/lubricant—incontrast to “wet machining”—is guided to the blades in a compressed airflow in an extremely low concentration. The lubricating medium istherefore supplied to the blades as an aerosol during machining, withthe aim of producing a sufficient lubricating film in the directvicinity of the cutting edges.

With MQL technology it is however necessary to conduct the lubricant tothe blades in a precise dosage and as constant a concentration aspossible. In order to achieve this object while at the same timereducing the fabrication outlay for producing the tool, the document DE202004008566 U1 describes a high-speed reamer in which a sleeve on thechucking section extends as far as the flute runout region of the tool,wherein the sleeve is configured in one piece with the chucking sectionand receives the reamer shank in the interior in order to form axialcoolant/lubricant channels. The lubricant channels which extend axiallyare supplied by a central lubricant channel in the chucking section insuch a manner that the cooling channel has a constant cross section fromthe shank end as far as the flute runout region.

In the two known cases, the supply of the blades with coolant/lubricantcan only be achieved by a correspondingly high outlay on the productionof the tool. Furthermore, the known tools must be assembled fromdifferent components.

BRIEF SUMMARY OF THE INVENTION

The invention is therefore based on the object of creating a rotatablydrivable cutting tool, of the type described above, which ensures thecurrently required service life of the blades and a simplified structureof the tool. A further object consists in creating a new method withwhich a fluid (for example, a coolant and/or lubricant) can be appliedto highly loaded blades of a generic tool with low outlay but reliablyand in sufficient quantities in both wet and dry machining (MQLtechnology).

This object is achieved by the methods and devices disclosed herein.

In some embodiments, coolant/lubricant channels are integrated in thechucking section of the tool in such a manner that the coolant/lubricantwhich emerges axially from these coolant/lubricant channels is guided onthe outer side of the shank which leads to the cutting section to ineach case one flute of the cutting section. It has been discovered bymeans of experiments that, with this design of the tools, both in whatis known as wet machining, that is, with the use of liquidcoolant/lubricants, and in what is known as “dry machining” according toMQL technology, a sufficient lubricant supply can be stabilized in theregion of the flutes and also at the faces of the tool blades which arecritical for the service life, even if the working pressure of thecoolant/lubricant is kept at an easily controllable level of, forexample, over 5 bar.

Investigations of the coolant/lubricant flow along the tool axis, thatis, from the chucking section to the tool tip, have shown that the fluidjet emerging from the coolant/lubricant channels has a sufficientlygreat core region with a high flow speed at the moment at which the toolpenetrates the bore to be machined, in particular the through-bore whichis to undergo fine post-machining, even if it has to cover aconsiderable axial length in the direction of the cutting head under theaction of the arising centrifugal forces, without a radially outerlimit. With increasing engagement length of the tool blades in thethrough-bore, even an increasingly stable flow profile forms in theindividual flow channels which are defined by the flutes and the borewalls. This ensures that the tool blades are supplied with sufficientquantities of coolant/lubricant, in particular in the regions in whichit is particularly important. Because the flow in these flow channels ismore and more pronounced with increasing distance from the workpiecesurface, the relatively highly loaded tool blade in the vicinity of thetool tip is also effectively cooled and lubricated. As a result, theservice life of the tool can be kept at a high level.

The measures disclosed herein produce the additional advantage that thecoolant/lubricant jets which emerge from the end-face discharge openingsin the chucking section can be used particularly effectively fortransporting away the swarf in the feed direction of the tool. Thiscreates the possibility of equipping high-speed fine machining tools,such as high-speed reamers, with the above-mentioned integratedcoolant/lubricant supply system.

Such high-speed reamers are operated at considerable cutting speeds. Ithas been shown however that the individual jets which emerge from theaxial discharge openings are sufficiently stable to bring about theabove-described effect of reliably filling the flow channels which arebounded by the flutes of the engaged cutting section, even withconsiderable centrifugal forces acting on the fluid jets and even atcomparatively low flow medium pressures in the order of magnitude ofapproximately 5 bar, that is, flow medium pressures which are easily inthe range of working pressures of conventional coolant/lubricant supplyunits. On the whole, the concept of tool design according to theinvention therefore produces the advantage that the absolute quantity ofcoolant/lubricant in the flutes can be considerably increased by thesupply of the coolant/lubricant on the outside. The supply ofcoolant/lubricant to the points which are critical for the tool islow-loss, since deflections of the coolant/lubricant flow are avoided.The concept according to the invention is thus suitable not only for wetmachining but also for what is known as dry machining or for minimalquantity lubrication (MQL technology). The flow speed, which isincreased by the design according to the invention, of thecoolant/lubricant in the flutes or in the swarf space in the axialdirection can be used effectively to transport away swarf.

The integration of the coolant/lubricant supply system in the tool alsocreates the possibility of constructing the tool in one piece and with alow mass. This then produces particular advantages if the tool consistsof a sinterable hard material, for example a solid hard metal or acermet material, at least in the region of the chucking section and theadjacent shank. For example, if a VHM reamer with a nominal diameter of8 mm is to be produced, a material saving on raw material of over 20%can be achieved. Since the design of the coolant/lubricant supply systemintegrated in the tool manages with a greatly reduced tool volume in theregion of the shank and the chucking section, the additional economicadvantage of a reduced material removal rate is produced whenmanufacturing the tool. It is for example sufficient to grind the flutesjust in the region of the cutting section. In the remaining region ofthe tool, that is, in the region of the shank and the chucking section,a cutting machining process can be completely omitted. The innercoolant/lubricant channels in the chucking section, and whereapplicable, the outer guide channels in the shank, can be createdlargely with its final dimensions as early as during fabrication of asintered blank.

With respect to the method, it has been shown that the above-describedaspect of sufficient supply with coolant/lubricant at the criticalpoints of the cutting section can easily be ensured if thecoolant/lubricant is supplied at a—previously customary—pressure of over5 bar. The particular features of the respective application of the toolcan be taken into account by varying the system pressure. For example,the system pressure is increased correspondingly with increasing lengthof the tool shank and/or with increasing centrifugal force acting on theindividual coolant/lubricant jets. Advantageous configurations of theinvention are the subject of the dependent claims.

If the coolant/lubricant channels in the chucking section in each casecontinue into a guide depression which is formed in the shank and isrouted to the associated flute of the cutting section, the individualcoolant/lubricant jets are additionally stabilized on the way to theflutes, as result of which the coolant/lubricant throughput in theregion of the cutting section, and thus the blade-cooling andswarf-transporting effects as described above, are further increased.

At the same time, a further increased saving in material is produced inthe case where the tool is manufactured from a sinterable material suchas solid hard metal or a cermet material. In this case the particularadditional advantage is produced that the recesses which are necessaryfor integrating the coolant/lubricant supply system can be produced orprepared with exact shaping and good dimensional accuracy as early as inthe blank of the tool, as a result of which the necessary materialremoval rate when producing the tool can be further reduced.

The coolant/lubricant channels which are formed in the chucking sectioncan be radially open on the circumferential side. The coolant/lubricantchannels are then closed by the chuck in the region of the chuckingsection.

In order to obtain more freedom for the geometric design of the crosssection of the coolant/lubricant channels in the chucking section whilerealizing great chucking forces, it is of particular advantage to designthe coolant/lubricant channels in the chucking section to be closed onthe circumferential side. These inner channels can be introduced, forexample extruded, as early as into the sintered blank with lowproduction outlay and a high degree of shape accuracy when sinteredmaterials such as solid hard metal or cermet materials are used. Afurther material saving on raw material is thereby produced. The shapingof the inner channels is accurate enough to achieve the effects ofcoolant/lubricant supply described at the start without having tosubject the inner channels to a post-machining step. In addition, animproved stability of the tool is produced, which has advantages withrespect to improved vibration damping and torque transmission.

A particularly good supply of the blades with coolant/lubricant and aparticularly good transporting of the swarf, even if this is produced inlarge amounts, as is the case for example with high-speed reamers, maybe produced with the development of, for example, fluid channels in thechucking section which are radially open. The flutes of a generic toolcan have a comparatively complex shape. However, such complicated shapesof the cooling channel section can be realized with a good level ofshape accuracy as early as in the sintered blank in particular if thecoolant/lubricant channels which are provided in the chucking sectionare introduced in the preliminary forming process, such as in anextrusion process or a pressing process. With these measures, a maximumcoolant/lubricant volumetric flow can be provided at such a radialdistance from the tool axis that a particularly strong and pronouncedcoolant/lubricant flow is built up and stabilized in the flutes in theengagement region of the tool, as a result of which the performance ofthe tool is further improved.

In some embodiments, the cross section of the discharge opening of theinner coolant/lubricant channel in the chucking section completelycovers the flute in the cutting section or is at least coextensive withthe said flute, as viewed in an axial projection.

The advantages as described above still apply to a substantial extent ifthe flute is radially offset towards the inside by a certain amount withrespect to the coolant/lubricant jet. This makes it possible for toolswith different nominal working diameters to be produced from one and thesame tool blank with inner coolant/lubricant channels in the chuckingsection. In that case, the chucking section and the geometry of theshank are kept the same, and a cutting machining process is carried outto varying extents to the final dimensions of the nominal workingdiameter, and/or of the flutes only, in the region of the cuttingsection. The flutes which are introduced into the cutting section thenrun either flush or with a slight transition into the guide depressionswhich are present in the shank for the individual coolant/lubricantjets.

Experiments have shown that when the flute in the cutting section isradially offset somewhat towards the inside with respect to the crosssection of the coolant/lubricant jet, the geometry of the cross sectionof the axial discharge opening should be matched to the geometry of theflute so that a speed profile is produced in the flutes in theengagement region of the tool which ensures particularly good supplywith lubricant at the cutting face.

The cross section of the axial discharge opening can be adapted in termsof its position and/or shape to the geometry of the associated flute insuch a manner that as great a coverage as possible of the relevantcross-sectional areas is produced in axial projection. Depending on theapplication, the chucking section can have a different diameter from thecutting section. In order nevertheless to ensure sufficient supply ofthe cutting section with coolant/lubricant at the critical points insuch a case, the coolant/lubricant channels in the chucking section canbe routed at an approach angle to an associated flute of the cuttingsection. Cutting sections of a wide variety of sizes can be suppliedwith coolant/lubricant in this manner by varying the approach angle ofthe coolant/lubricant channels, without having to change the (standard)diameter of the chucking section of the tool.

If the coolant/lubricant channels are angled towards the tool axis, theguide depressions should also be routed towards the associated flute ofthe cutting section at an approach angle, preferably the same approachangle, in order to stabilize the coolant/lubricant jet.

Particularly good stabilization of the coolant/lubricant jet whichemerges from the chucking section may be produced with the developmentof, for example, channels which each emerge from the chucking sectionsat an approach angle (α) to an associated flute. When the tool isproduced from a hard material such as a sintered material such as hardmetal or cermet, the stepless transition of the coolant/lubricantchannels which are formed in the chucking section into the associatedguide depressions in the shank can be produced as early as in the blank,that is, by a preliminary forming process. It is however likewisepossible for this stepless transition to be produced by cuttingmachining of the guide depressions, for example by grinding the guidedepressions.

In some embodiments, the loading of the flutes with individual, axiallyaligned coolant/lubricant jets is important for adequate supply of thetool blades with coolant/lubricant. In some embodiments, the tool canhave one or more flutes that are not straight. For example, the flutescan also run in a spiral manner. If the flutes run in a straight line,that is, in an axially aligned manner, an even greater filling level ofthe flutes with coolant/lubricant can be achieved in the engagementregion of the cutting section. This produces the further advantage thatthe production method is simplified, in that the grinding disc forgrinding the flutes can at the same time be used for producing the guidedepressions in the shank of the tool. Moreover, a tool which hasstraight flutes allows the tool to be produced in one piece in anextrusion process, which is particularly advantageous if a hardmaterial, preferably a sintered material such as solid hard metal orcermet, for example, is used as the material.

If at least the shank and the chucking section of the tool is producedfrom sinterable material such as solid hard metal or a cermet material,the coolant/lubricant channels in the chucking section and whereapplicable the guide depressions in the shank can be preformed in thetool blank to such an extent that post-machining after the sinteringprocess is either no longer necessary at all or can remain restricted toa minimum. In addition to improved cost-effectiveness during productionof the tool, material outlay on the required raw material is also at anminimum.

The rotatably drivable cutting tool can have a wide variety ofapplications. It can be configured for example as a fine machining tool,as a drilling tool, e.g., as a reamer, as a milling tool or as athread-cutting tool. The tool in other embodiments is configured with anon-uniform distribution of the blade flutes around the circumference.In this manner, the supply of the blades with coolant/lubricant can beensured for all the flutes with the same quality without having toincrease outlay on production. Flow medium pressures in the range from,for example, 5 to 70 bar, are sufficient for the adequate supply of theengaged blades of the tool for current geometries of the tools inquestion. This makes it possible to work with flow media of differentconsistencies, for example with liquid coolant/flow media, but also withaerosols as are used in dry machining or MQL technology.

In some embodiments, it is possible to stabilize the individualcoolant/lubricant jets which emerge from the chucking section in orderto bridge longer axial distances between the chucking section and thecutting section in such a manner that the individual coolant/lubricantjets reach the associated flutes with the greatest area coveragepossible.

BRIEF DESCRIPTION OF THE DRAWINGS

A plurality of embodiments are explained in more detail below with theaid of schematic drawings, in which:

FIG. 1 shows a schematic side view of a rotatably drivable cutting toolaccording to the present inventive subject matter, configured as areamer, according to a first embodiment;

FIG. 2 shows the view according to “II” in FIG. 1;

FIG. 3 shows the view according to “III” in FIG. 1;

FIG. 4 shows section “IV-IV” in FIG. 1 in an enlarged illustration;

FIG. 5 shows section “V-V” in FIG. 1 in an enlarged illustration;

FIG. 6 shows detail “VI” in FIG. 2 in an enlarged illustration;

FIG. 7 shows a side view corresponding to FIG. 1 of a modifiedembodiment of a cutting tool according to the present inventive subjectmatter wherein the tool according to FIG. 7 can be produced from thesame blank as that of FIG. 1;

FIG. 8 shows the view according to “VIII” in FIG. 7 in a slightlyenlarged illustration;

FIG. 9 shows the view corresponding to “IX” in FIG. 7;

FIG. 10 shows the sectional view according to “X-X” in FIG. 7 in anenlarged illustration;

FIG. 11 shows the view of section “XI-XI” in FIG. 7;

FIG. 12 shows detail “XII” in FIG. 8 in an enlarged illustration;

FIG. 13 shows a schematic view of a third embodiment of a tool accordingto the present inventive subject matter, shown, configured as a reamer;

FIG. 14 shows the view according to “XIV” in FIG. 13 in a greatlyenlarged illustration;

FIG. 15 shows a perspective view of the tool according to FIGS. 13 and14;

FIG. 16 shows a longitudinal section of the tool according to a fourthembodiment or the present inventive subject matter; and

FIG. 17 shows a longitudinal section of the tool according to a fifthembodiment of the present inventive subject matter.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 6 show a first embodiment of a rotatably drivable cuttingdrilling post-machining tool configured as a reamer, such as ahigh-speed reamer. The rotatably drivable cutting fine machining tool,which is indicated with the reference numeral 20, may be configured inone piece and may consist of a sintered material such as solid hardmetal or a cermet material, for example, a sintered material whichcontains the carbides and nitrides of titanium (TiC, TiN) as theessential hardening constituents and in which nickel is predominantlyused as the binder phase.

The tool has three sections, namely a chucking section 22, a cuttingsection 24 and a shank section 26 which is arranged between them and hasa reduced diameter. The cutting section 24 is grooved in straight linesand has a plurality of cutting edges 28 between which a flute 30 issituated in each case. The flute has essentially two flanks, namely afirst flank 32 which leads towards the cutting edge and a second flank34 which runs at an angle to this, and a rounded flute base 36 whichlies between them (see FIG. 6). The cutting edges 28 are distributeduniformly over the circumference in the embodiment according to FIGS. 1to 6. The distribution can however be non-uniform, which in high-speedreamers which run at high speed has the advantage of improved runningsmoothness and a reduced tendency to vibrate.

The special feature of the tool shown in FIGS. 1 to 6 consists in theconfiguration of the coolant/lubricant supply system which is integratedin the tool and is described in more detail below.

Inner cooling channels 38 are formed flush with the flutes 30 in theaxial direction in the chucking section 22 and extend in each caseparallel to the tool axis 40 and in each case form an axial discharge ormouth opening 42 on the side of the chucking section 22 which faces thecutting section 60. The cross sections of the inner coolant/lubricantchannels 38 and thus the mouth openings 42 are essentially coextensivewith the cross section of the flutes. In particular, the cross sectionof the respective axial discharge opening 42 for the coolant/lubricantjet is provided with a cross section which is adapted to the crosssection of the associated flute 30.

In the configuration according to FIGS. 1 to 6, the cross section of theaxial discharge opening 42 corresponds to the geometry of the associatedflute 30 in the region of the flute base 36 and the two flute flanks 32and 34. Only the radial extent of the mouth opening 42 is reduced by themeasure T of the remaining wall thickness in the chucking section 22compared to the depth of the flute 30.

A guide depression 44, which forms the axial extension of the flute 30and is largely coextensive with the flute 30 in the section according toFIG. 5, extends between the discharge or mouth opening 42 and the flute30. In other words, the guide depression has essentially the shape ofthe flute with the flanks 32 and 34 and the flute base 36 between them,viewed in cross section.

When the tool is chucked in a tool holder, coolant/lubricant is fed at apressure of, for example, 5 to 70 bar by means of a suitable interfaceon the right-hand side in FIG. 1 of the chucking section 22. This can beliquid or gaseous flow medium which transports the lubricant, forexample an aerosol, that is, compressed air which is mixed withlubricant droplets. The direction of rotation of the tool is indicatedin FIG. 5 with the arrow RD.

The coolant/lubricant which is fed by means of a conventional interfacein the chucking section 22 thus flows at high speed through thecoolant/lubricant channels 38 which are formed in the chucking section22 and emerges with an axial alignment at the mouth openings 42. Theindividual coolant/lubricant jets are guided in the radially innerregion by the base and the flanks of the guide depression 44, theindividual coolant/lubricant jets are open in the radially outer region.

The individual coolant/lubricant jets which are distributed over thecircumference according to the division of the tool meet the flutesafter flowing through the guide depressions 44. As soon as the toolpenetrates the bore, preferably a through-bore, to be machined, theflute is as far as possible closed over its entire circumference by thebore walls so that a virtually closed flow channel is created again forthe fed coolant/lubricant. The flow medium which comes in this flowchannel from the associated inner coolant/lubricant channels 38 and iscollected has—as could be shown by experiments—such a high massthroughput, even at flow medium system pressures of over 5 bar,preferably of over 10 bar, that a flow profile is formed in the fluteswhich ensures that the cutting edges are reliably supplied with asufficient quantity of lubricant. This ensures that the service life ofthe tool can be kept at an adequate level.

It was discovered by means of experiments that the through-flow quantityof the coolant/lubricant in the flutes depends on the profile shape ofthe coolant/lubricant channels which are formed in the chucking section.

The outer supply of the coolant/lubricant and the cross section, whichis enlarged according to the present inventive subject matter, of theinner coolant/lubricant channels in the chucking section 22 ensure thatthe quantity of coolant/lubricant which is guided to the blades can beconsiderably increased compared to tools with a central, inner supplychannel. This can be used not only to improve the service life of theblades but also at the same time to improve the transporting away ofswarf.

The supply of the coolant/lubricant takes place in a very low-lossmanner in the tool according to the present inventive subject matter, asmultiple deflections are avoided. As a multiplicity of comparativelyextensive coolant/lubricant channels are formed in the chucking sectionand additionally guide depressions are formed in the shank of the tool,a low weight and a low requirement for raw material is produced for thetool in the event that the tool is produced from a sintered blank.

The inner coolant/lubricant channels in the chucking section, the guidedepressions in the shank and also the flutes in the cutting section canbe produced as early as in the sintered blank as far as possible withthe final dimensions in the preliminary forming process. Machining ofthe inner cooling channels in the chucking section is then no longernecessary. The grinding of the guide depressions in the shank canlikewise be omitted completely or restricted to a minimum. Cuttingmachining operations, namely grinding to final dimensions, are then onlynecessary in the region of the cutting section, as a result of which agreatly reduced material removal rate is produced in the production ofthe tool.

A further embodiment of the tool is described using FIGS. 7 to 12. Thecomponents of the tool which correspond to those of the embodimentaccording to FIGS. 1 to 6 are provided with similar reference symbols,but with a “1” in front.

The tool according to FIGS. 7 to 12 can be produced from the same blankas that of FIGS. 1 to 6. The tool is however designed for a smallernominal working diameter.

The embodiment according to FIGS. 7 to 12 thus differs from theembodiment according to FIGS. 1 to 6 in that the nominal workingdiameter of the cutting section 124 is reduced compared to that of thetool of FIGS. 1 to 6. This means that the outer diameter of the shanksection 126 is also smaller, whereas the chucking section 122 isconfigured identically to the chucking section 22 of FIGS. 1 to 6.

Owing to the reduced outer diameter D126 of the shank 126, the guidedepressions 144 in the shank section 126 are flatter than in theembodiment according to FIGS. 1 to 6. It can be seen from FIG. 10 thatthe inner coolant/lubricant channels in the chucking section 122 againmerge steplessly into the associated guide depressions 144.

However, the flutes 130 in the region of the cutting section 124 arefurther radially inside than the coolant/lubricant channels 138 or theguide depressions 144, which can be seen best in FIG. 12. A transitionsection 146 is situated between the flutes 130 and the guide depressions144, in which transition section the guide depression 144 graduallywidens radially inwards towards the flute 130. There is thus a gentletransition of the base face from the guide depression 144 to the flutebase 136 of the flute 130.

The supply of coolant/lubricant to the cutting edges 128 takes place inthe same manner as in the tool described above using FIGS. 1 to 6.

The coolant/lubricant which emerges from the mouth openings 144 flows ina guided manner through the guide depressions 144 in the axial directionto the cutting section 124. The coolant/lubricant jets can widenslightly in a radially inward direction in the region of the transitionfaces and meet in the flutes 130. As can be seen best in FIG. 12, theaxial discharge openings or the cooling channels 138 have a crosssection which is adapted, that is, is geometrically similar to the crosssection of the associated flute 130. In other words, the geometry of thecross section of the coolant/lubricant channels 138 in the region of theflanks and the radially inner limit corresponds to the contour of theflute 130, that is, in the region of the flute base 136 and of the flank132 which leads to the cutting edge 128.

In this manner an adaptation of the cross section of the axial dischargeopening 142 with respect to position and/or shape is produced to thegeometry of the associated flute 130 in such a manner that the greatestpossible coverage of the relevant cross-sectional areas is produced inthe axial projection, which is indicated in FIG. 12 by a cross-hatchedarea 148.

The tool according to FIGS. 7 to 12 has been fabricated as a high-speedreamer with a nominal diameter of 6.2 mm from the same sintered blank asthe tool of FIGS. 1 to 6 with a nominal working diameter of 8 mm. Thethroughput of the coolant/lubricant in the region of the flutes in thetool of FIGS. 7 to 12 could be kept at a level which still amounts to60% of the coolant/lubricant throughput of the embodiment according toFIGS. 1 to 6. The pressure of the flow medium which guides the lubricantwas in the range from 10 to 70 bar.

For these flow medium pressures it could be shown that the centrifugalforce acting on the individual coolant/lubricant jets does not adverselyaffect the supply of the blades with a sufficient quantity ofcoolant/lubricant. Deviations in the respective throughput quantities ofcoolant/lubricant at the blades themselves were even smaller. The toolof FIGS. 7 to 12 can also be produced simply and with minimal outlay onraw material. The material removal rate during manufacture, that is,when grinding flutes, is likewise restricted to a minimum.

Finally, a third embodiment of a fine machining tool configured as ahigh-speed VHM reamer is described using FIGS. 13 to 15. In this casetoo, the components which correspond to the structural sections of theabove-described exemplary embodiments are provided with similarreference symbols, but with a “2” in front.

The reamer according to FIGS. 13 to 15 differs from the above-describedtools by an axially extended chucking section 222. The coolant/lubricantchannels 238 which are formed in this section and again lie on theoutside are formed by radially open slots which continue steplessly intoguide depressions 244 of the shank section 226. Flutes, indicated with230, merge via a rounded transition face 246 into in each case one guidedepression 244. When the tool is accommodated in the tool holder, thecoolant/lubricant channels are radially outwardly closed by the chuck.

The position and geometry association between the coolant/lubricantchannel 238, guide depression 244 and flute 230 can be seen in detail inthe illustration according to FIG. 14. It can be seen that a flank 250of the slot 238 is placed such that it essentially coincides with theflank 232, which leads to the cutting edge 228, of the flute.

In the configuration according to FIGS. 13 to 15, it is for example acermet reamer with a nominal diameter of 4 mm. The blank for the toolaccording to FIGS. 13 to 15 can thus be used just as well for a reamerwith a nominal diameter of up to 5.5 mm. It has however been shown inexperiments that even with a nominal diameter of 4 mm, which is small incomparison to the chucking section, enough coolant/lubricant can beconducted by the individual axially aligned coolant/lubricant jets tothe cutting edges 228 in the engagement region of the tool to ensure thedesired improvement in the service life. The tool of FIGS. 13 to 15gives an even more increased material saving in raw material for thesintered blank, as the inner coolant/lubricant channels in the chuckingsection are even more enlarged in area. The transition section 246between the flute 230 and the guide depression 244 can be producedsimply by using a grinding disc with a large enough radius to grind theflutes 230.

In the configuration of the tool according to FIGS. 13 to 15 as well,the cross section of the axial discharge opening of the innercoolant/lubricant channels thus essentially corresponds to the geometryof the associated flute 230 at least in the region of the flute base 236and of the flute flank 232 which leads to the cutting edge 228, as aresult of which the quantity of lubricant which arrives at the cuttingedges can be kept high enough even if only a fraction of the crosssection of the flute is covered by the cross section of thecoolant/lubricant jet, viewed in axial projection.

A fourth embodiment of the tool is described using FIG. 16. Thecomponents of the tool which correspond to those of the embodimentaccording to FIGS. 1 to 6 are provided with similar reference symbols,but with a “3” in front.

The fourth embodiment corresponds essentially to the first embodimentwith the exception that the coolant/lubricant channels 338 in thechucking section 322 do not extend parallel to the tool axis 340 but arerouted towards it at an approach angle α. The approach angle α isselected to be such that an imaginary extension of the coolant/lubricantchannels 338 beyond the shank section 326 which lies in between isessentially aligned with the flutes 330 of the cutting section 324.Corresponding guide depressions on the shank section, in axial extensionof the coolant/lubricant channels 338, extend between the mouth openings342 and the flutes 330, which guide depressions are likewise set at theangle α with respect to the tool axis.

In the fourth embodiment shown in FIG. 16, the flutes 330 of the cuttingsection 324 lie on a greater pitch circle than the discharge openings342 of the coolant/lubricant channels 338. However the reverse situationis also conceivable. The setting of the coolant/lubricant channels 338towards the tool axis 440 means that the diameter of the chuckingsection 322 can be designed independently of that of the cutting section324, and a resulting approximate difference in the radial distances ofthe mouth openings 342 and of the flutes 330 from the tool axis 340 canbe compensated.

FIG. 17 shows a fifth embodiment of the tool. The components of the toolwhich correspond to those of the embodiment according to FIGS. 13 to 16are provided with similar reference symbols, but with a “4” in front.

The tool shown in FIG. 17 has radially open coolant/lubricant channels438 in the chucking section 422, which are guided at an approach angle αto the tool axis 440 and are aligned via corresponding likewise angledguide depressions 444 on the shank section 426 essentially with theflutes 430 of the cutting section 424.

Of course, deviations from the described exemplary embodiments arepossible without departing from the basic idea of the invention.

It is thus, for example, not absolutely necessary for the cutting headto be formed in one piece with the rest of the tool. The cutting headcan also be attached in a rotationally and axially fixed manner to theshank in a known manner, for example, soldered. The above-discussedadvantages are all retained in this variant.

The tool itself does not necessarily have to be produced from a sinteredmaterial either.

The different functional sections of the tool can furthermore beprovided with coatings which are known per se. Finally, the cuttingsection of the tool can also be equipped with cutting inserts.

All the above-described embodiments have been shown as reamers. Itshould however be emphasized that the tool can likewise be configured asa conventional drilling tool, as a milling tool or as a thread-cuttingtool, etc.

If it is a tool which has straight flutes, additional advantages areproduced in its production, in particular if the tool is produced from asintered material blank which can for example be extruded or formed in apressing process with already incorporated inner coolant/lubricantchannels and/or guide depressions and/or prepared flutes.

The cutting section can however also be equipped with spiral flutes. Inthis case it can be advantageous if the cutting section is attached tothe shank as a separate component.

The angled coolant/lubricant channels of the fourth and fifthembodiments can also branch off directly from a centralcoolant/lubricant channel. As a result, corresponding radial connectionchannels between the coolant feed and the coolant/lubricant channelswhich are at a distance from the tool axis and are distributed in thecircumferential direction, are unnecessary.

The subject matter disclosed herein thus creates a rotatably drivablecutting tool, for example, configured as a fine machining tool such as ahigh-speed reamer, with an integrated coolant/lubricant supply system,for machining bores, for example, through-bores. The tool has a cuttingsection, on which a multiplicity of blades or cutting edges and flutesare formed, and a shank section which forms a chucking section on a sidewhich faces away from the cutting section. In order to supply thecutting edges effectively with coolant/lubricant while at the same timeimproving the cost-effectiveness of the production method, a number ofcoolant/lubricant channels which corresponds to the number of flutes isformed in the chucking section, which channels have in each case anaxial discharge opening and are routed along the shank to an associatedflute of the cutting section.

1. A tool comprising: a cutting section, on which a multiplicity ofblades or cutting edges and flutes are formed; a shank section, whichforms a chucking section on a side which faces away from the cuttingsection, wherein a number of fluid channels which corresponds to thenumber of flutes is formed in the chucking section, which channels ineach case have an axial discharge opening and lead along the shank to anassociated flute of the cutting section.
 2. The tool according to claim1, wherein the shank section comprises a plurality of guide depressions,and wherein each channel leads to a corresponding guide depression,which leads to a corresponding flute in the cutting section.
 3. The toolaccording to claim 1, wherein said fluid channels in the chuckingsectionare closed on the circumferential side.
 4. The tool according toclaim 1, wherein the fluid channels in the chucking section are radiallyopen.
 5. The tool according to claim 1, wherein each of the axialdischarge openings comprises a cross section which is adapted to thecross section of the associated flute.
 6. The tool according to claim 5,wherein the cross section of each of the axial discharge openingscorresponds to the geometry of the associated flute base and of theassociated flank which leads to the associated cutting edge.
 7. The toolaccording to claim 5, wherein each of the cross sections of the axialdischarge openings is adapted in terms of its position and/or shape tothe geometry of the associated flute in such a manner that as great acoverage as possible of the relevant cross-sectional areas is producedin axial projection.
 8. The tool according to claim 5, wherein each ofsaid channels emerge from the chucking section at an approach angle (α)to an associated flute.
 9. The tool according to claim 2, wherein eachof the guide depressions is routed to a corresponding flute of thecutting section at an approach angle (α).
 10. The tool according toclaim 1, wherein each of said fluid channels in the chucking section inthe radially inner region merge steplessly into the associated guidedepressions.
 11. The tool according to claim 1, wherein each of saidflutes runs in a straight line.
 12. The tool according to claim 1,wherein the tool comprises a sintered material.
 13. The tool accordingto claim 12, wherein the shank section comprises a plurality of guidedepressions, and wherein each of the guide depressions and the fluidchannels in the chucking section are at least partially preformed in thetool blank.
 14. The tool according to claim 1, wherein the tool is adrilling tool.
 15. The tool according to claim 1, wherein the tool is amilling tool.
 16. The tool according to claim 1, wherein the tool is athread-cutting tool.
 17. A method for supplying the blades of a toolaccording to claim 1 with a pressurized fluid, wherein the fluid issupplied via the chucking section at a pressure of about 5 bar to about80 bar.
 18. The method according to claim 17, wherein said fluid isformed from an aqueous flow medium.
 19. The method according to claim17, wherein said fluid is formed from a gaseous fluid which is mixedwith a flow medium.
 20. The method according to claim 17, wherein theflow of the fluid in the chucking section is loaded with a swirl aboutthe flow axis.
 21. The method according to claim 17, wherein thepressure is about 10 bar to about 70 bar.
 22. The tool according toclaim 1, wherein the tool is a rotatably drivable cutting tool.
 23. Thetool according to claim 1, wherein the tool is a reamer.